1. Field of the Invention
This invention relates to aerosol dispensers and containers therefor. In particular, it relates to aerosol dispensers which utilize dispensing pumps which do not rely on an added propellant gas.
2. The Related Art
Dispensing pumps are known which can be fitted to dispensing containers, and can be used for dispensing the liquid contents of the containers where the container does not contain any added propellant gas, such as hydrocarbons or chlorofluorocarbons. Instead, the container or the dispensing pump contains a mechanism by which atmospheric air can be introduced into the container to produce a positive pressure, which may be used to provide the required pressure for the liquid to be adequately dispensed in aerosol form.
Such systems are conveniently known as "user pressurised dispensers". An example of such systems is described in GB 1582556 (Airspray), which describes an aerosol dispensing mechanism incorporating a one-way valve and plunger system, which can be used to introduce atmospheric air into a container to which it is attached.
A further development of this aerosol dispensing mechanisms is described in EP 238 611 (Airspray). These aerosol dispensing mechanisms are self-contained units, which conventionally attach to ordinary bottles by means of a simple collar piece, which may be used to attach the aerosol dispensing mechanism to the bottle by simply screwing the collar onto a thread located around the neck of the bottle.
A claimed advantage of such aerosol dispensing mechanisms is that, when they are used on a commercial scale to dispense e.g. hair spray or aerosol deodorants, it is possible to buy the liquid hair spray or deodorant in a so-called "refill" pack. The refill pack can then be used either to decant the liquid product into the original container, or may be attached, via the aforementioned screw-on collar, onto the aerosol dispensing mechanism.
However, it is a recognised characteristic of user pressurised systems, in particular those which utilise the aerosol dispensing mechanism described in EP 238 611 (the so called "dry spray" unit) that the container holding the liquid product to be dispensed must not be completely filled with liquid product. In particular, as far as possible, the liquid product in the container should not come into contact with the aerosol dispensing mechanism during the act of dispensing the product, since such contact nullifies the advantageous effects of using this aerosol dispensing mechanism.